Like all industries, the maritime industry has developed it's own language and terminology which in some cases varies from port to port and specific use to specific use. However, many of the terms are widely used and should be understood.
Cargo ships have a large number of abbreviations and terms to define very common items. "DWT" or deadweight tonnage refers to the total lifting capacity of a ship, expressed in long tons of 2,240. "Displacement" refers to the weight of a ship, expressed in either long tons or metric tons (2,205 lbs.), equivalent to the weight of water displaced by the ship as it floats. "LDT" or light ship displacement is the weight of the ship, excluding cargo, fuel, ballast, stores, passengers, and crew.
"Deck Load" refers to the weight that can be carried on a flat deck surface. Often, you will see the term "Grain/Bales" followed by a cubic measurement. This is indicative of the maximum space available for cargo within a ship's holds in cubic feet.
The primary difference between the measurement of "grain" capacity and "bales" capacity is that a cargo such as grain, wheat, cement or any "flowing" cargo fills up all of the voids within the cargo hold. The "bale" measure excludes areas within the cargo hold that baled cargo cannot fit. Consequently, the capacity is less.
Container ships move most of the world's cargo. These ships are designed for stowage of containers in vertical stacks or cells either within the hold of the vessel, on deck, or a combination of the two. Containers are described in "FEU's" or "TEU's". An "FEU" is a forty-foot long container and an "TEU" is a twenty-foot long container. The abbreviation stands for "Forty foot Equivalent Unit" or a Twenty foot Equivalent Unit."
There are seven basic types of containers. These include: Refrigerated containers; dry bulk containers; rack containers for lumber, etc; automotive containers; livestock containers; and collapsible containers for stowing when not in use